Analysis On Damaged Habitat Characteristics Ofguishui River And Therestoration By Aquatic Plant Community

Affected by population growth and the expansion of economic scale,river ecosystem has suffered different degrees of destruction,river ecological service function decline,degradation phenomenon is prominent,repair and solve the problem of river damaged habitat has become one of the core issues of widespread international concern.Taking the GuishuiRiver in Beijing as the research object,this paper constructs the evaluation index system of water shortage river habitat in the north under the condition of systematic diagnosis of the damaged habitat of Guishui river,and carries on the comprehensive quality evaluation according to the habitat characteristics of different river segments.At the same time,the pilot experiment of aquatic plant community configuration was carried out to screen the distribution model of aquatic plant communities suitable for the habitat conditions of Guishui River,in order to achieve the restoration goal of river damaged habitat by ecological means,and to provide scientific basis for the rapid start and repair of damaged habitats of Gui river.The research results are as follows:（1）The present situation of the study area is generally good,but there are poor water system connectivity in some river sections,obvious shortage of river ecological quantity,poor water flow,turbidity of water quality and other habitat damage problems,in which Sanli River section of the tributary is seriously affected by human disturbance,the river channel is invaded,the function of the wetland is gradually degraded,and the concentration of TP,NH₄⁺-N and COD_Cr in the river water is high,which belongs to the national surface water environment standard and is inferior to the V type water body.The Gucheng River section is cut off all the year round,and the ecological base flow is difficult to guarantee,the river boundary of the Guishui River and some tributaries are blurred,and the farmland reclamation,illegal construction and woodland encroachment are serious.（2）The comprehensive quality evaluation reflects the actual situation of river habitat under the condition of water shortage and drought in the north.The habitat quality of the Guishui River is generally good,and the habitat quality ranksare good,better,general,poor,and the worst river sections account for 46.2%,15.2%,7.7%,23.1%,7.7%.Habitats in gentle slope type rivers belong to the“good”grade,and mountainous and urban river sections belong to the“poor”grade.（3）Five single aquatic plant communities showed significant removal effects on TN,NH₄⁺-N,NO₃^--N,TP and PO₄^3--P.The removal rates of TN and NO₃^--N were as follows:M1 Acorus calamus>M4 Batrachium bungei>M2 Ceratophyllum demersum>M5Myriophyllum verticillatum>M3 Vallisneria natans.The removal rates ofTP were as follows:M2 Ceratophyllum demersum>M3 Vallisneria natans>M1 Acorus calamus>M4 Batrachium bungei>M5 Myriophyllum verticillatum.The removal rates of PO₄^3--P were as follows:M5Myriophyllum verticillatum>M4 Batrachium bungei>M1 Acorus calamus>M3 Vallisneria natans>M2 Ceratophyllum demersum.The removal rates ofTP were as follows:M5Myriophyllum verticillatum>M4 Batrachium bungei>M2 Ceratophyllum demersum>M1Acorus calamus>M3 Vallisneria natans.On the whole,Acorus calamusand Myriophyllum verticillatum have good removal efficiency of nitrogen and phosphorus,respectively.（4）When the concentration of nitrogen and phosphorus in the water is high,the treatment group with better removal effect on TN,NH₄⁺-N and NO₃^--Nis N5Acorus calamus+Ceratophyllum demersum+Vallisneria natans+Myriophyllum verticillatum+Batrachium bungei（planting ratio 1:1:1:1:1）,N6 Acorus calamus+Ceratophyllum demersum+Vallisneria natans（planting ratio 1:1:1）and N7 Acorus calamus+Ceratophyllum demersum+Vallisneria natans+Batrachium bungei（planting ratio 1:1:1:1）.The treatment groups with better removal effect on TP and PO₄^3--P were:N5 Acorus calamus+Ceratophyllum demersum+Vallisneria natans+Myriophyllum verticillatum+Batrachium bungei（planting ratio 1:1:1:1:1）,N4 Acorus calamus+Ceratophyllum demersum+Vallisneria natans（planting ratio 1:1:2）,N7 Acorus calamus+Ceratophyllum demersum+Vallisneria natans+Batrachium bungei（planting ratio 1:1:1:1）.When the concentration of nitrogen and phosphorus in water is low,the combined ability of nitrogen and phosphorus in each combination plant community is not much different.By comprehensive comparison,it is found that the treatment group of N5 Acorus calamus+Ceratophyllum demersum+Vallisneria natans+Myriophyllum verticillatum+Batrachium bungei（planting ratio 1:1:1:1:1）not only shows strong ability to remove nitrogen and phosphorus,but also has rich community species and strong stability.It is a model of aquatic plant community configuration suitable for Guishui river habitat conditions.